Computer systems increasingly have access to a profusion of input information. For example, a computer may be able to receive instructions and other input from a user via a variety of input devices, such as a keyboard, various pointing devices, or an audio microphone. A computer may also be able to receive information about its surroundings using a variety of sensors, such as temperature sensors. In addition, computers can also receive information and communicate with other devices using various types of network connections and communication schemes (e.g., wire-based, infrared or radio communication).
Wearable personal computers (or “wearables”) can have even greater access to current input information. Wearables are devices that commonly serve as electronic companions and intelligent assistants to their users, and are typically strapped to their users' bodies or carried by their user in a holster. Like other computers, wearables may have access to a wide variety of input devices. Moreover, in addition to more conventional input devices, a wearable may have a variety of other input devices such as chording keyboards or a digitizer tablet. Similarly, a wearable computer may have access to a wide variety of sensors, such as barometric pressure sensors, global positioning system devices, or a heart rate monitor for determining the heart rate of its user. Wearables also may have access to a wide variety of non-conventional output devices, such as display eyeglasses and tactile output devices.
Many applications executing on computers utilize data received by the computer from sensors or other input sources. For example, a position mapping application for a wearable computer may utilize data received from a global positioning system device in order to plot its user's physical location and to determine whether that position is within a specified region. In this example, the global positioning system device produces data that is consumed by the position mapping application.
In conventional wearable computer systems, the position mapping application would be designed to interact directly with the global positioning system device sensor to obtain the needed data. For example, the application may be required to instruct the device to obtain position information, retrieve the information obtained by the device, convert it to conventional latitude and longitude representation, and determine whether the represented location is within the special region.
The need for such direct interaction between applications and sensors in order to obtain and process data has several significant disadvantages. First, developing an application to interact directly with a particular sensor can introduce sensor-specific dependencies into the application. Accordingly, the application may need to be subsequently modified to be able to interact successfully with alternatives to that sensor provided by other manufacturers, or even to interact successfully with future versions of the same sensor. Alternately, the sensor could be developed to explicitly support a particular type of application (e.g., via a device driver provided with the sensor), which would analogously introduce application-specific dependencies into the sensor.
Second, direct interaction between the application and the sensor can give rise to conflicts between multiple applications that consume the same data. For example, if the position mapping application was executing on the same wearable computer as a second application for determining the user's distance from home, and the second application also used the global positioning system device, the two applications' interactions with the device could interfere with one another.
Third, direct interaction between the application and the sensor can give rise to conflicts between multiple sensors that produce the same data. For example, if the position mapping application was executing on a wearable computer that had access to both the global positioning system device and an indoor positioning system, the application might well have trouble determining which device to use to determine the user's current position, and/or have trouble reconciling data produced by both devices.
Fourth, rather than an application having to directly process observable data from the sensors and derive more abstract information itself, it would be advantageous for the application to be able to rely on a separate programmatic entity that derives such abstract information and provides it to the application. For example, it would be more convenient for the position mapping application to be able rely on a separate programmatic entity that determines the user's location, and to then use that information to determine whether the user is in a special region.
Accordingly, a facility for exchanging information between sensors and applications in a wearable computer system would have significant utility.